In view of recent events, fuel economy for automotive vehicles has become of great importance. The rising cost of fuel and other considerations have driven manufactures of automotive vehicles to consider alternative fuel sources and systems such as hydrogen, solar power, fuel cells, hybrid gas/electric, and natural gas. Additionally, many hybrid vehicles combining various power transmission techniques have also been introduced to the market in recent years.
A vehicle that utilizes an alternative fuel source provides the advantage of avoiding the economic strain of the ever increasing cost of fossil fuel. However, this advantage does not come without an associated cost. For example, to realize the advantages of a vehicle that utilizes an alternative fuel source, a new alternative fuel source vehicle must be purchased or an existing fossil fuel type vehicle must be retrofitted to incorporate the alternative fuel source. Each of these alternatives requires a relatively high cost to effectuate.
Like all mechanical systems, a conventional internal combustion engine converts one form of energy (the combustion of air and fuel) to another form of energy (kinetic energy in the form of the rotation of the driveshaft of a vehicle). However, this conversion of energy is not without losses. For example, once the energy from the combustion of air and fuel has been converted to kinetic rotational energy in the driveshaft to propel the vehicle, an equivalent amount of energy is required to stop the vehicle. Stopping the vehicle is ordinarily accomplished with a conventional frictional braking system. A frictional braking system stops the vehicle by converting the kinetic energy of the vehicle in motion primarily into heat energy generated by the friction between the friction pad of the brakes and a rotor or a disc operatively connected to a wheel of the car. Once the kinetic energy of the car is converted to heat energy, the heat energy is absorbed by the vehicle itself and otherwise dissipated into the atmosphere. Once the heat energy is absorbed by the vehicle and dissipated into the atmosphere, it cannot be recaptured thereafter.
Given the above noted increasing costs of fuel, and that fossil fuel resources are considered to be limited, non-replenishable, and polluting, attempts have been made to utilize less fuel by recapturing the energy otherwise lost by a conventional frictional braking system using a regenerative braking system. Current regenerative braking systems typically incorporate a relatively complex system to recapture the energy otherwise lost during the braking of the vehicle. For example, some regenerative braking systems utilize a hydraulic system that incorporates a high pressure accumulator to recapture the energy otherwise lost during braking. Other systems incorporate the use of a fly wheel and complex belt and pulley system.
Unfortunately, the above-noted regenerative braking systems are relatively complex, add a significant amount of weight to the vehicle thereby reducing the overall fuel economy of the vehicle, and have reliability issues as a function of their complexity. Moreover, typical electrical regenerative braking systems utilize a complex series of generator motors and switches that rapidly switch on and off a charging cycle for a battery, resulting in a reduced life cycle of the battery itself and the associated electronic componentry. This rapid switching of the charge cycle also results in an inefficient charge cycle.
It is therefore desirable to have a regenerative braking system that can be quickly adapted to an internal combustion type vehicle, hybrid vehicle, or electrically powered vehicle at a relatively low cost. It is further desirable that such a regenerative braking system be embodied in a simplified, low-weight package that eliminates the rapid on/off charge cycle, thereby maximizing the efficiency of the same.
The invention provides such a regenerative braking system. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.